Word had already leaked that Demings would mount a campaign for Congress in 2012. But it wasn't clear until Wednesday whether the Orlando Democrat would run for Webster's seat in Florida's 8th District or in a new district whose boundaries won't be drawn until next year.

At her formal campaign announcement Wednesday afternoon, Demings cleared up the mystery: She'll try to unseat Webster, a Republican elected in 2010.

In 2007, Demings, 54, became the first black woman to run the Orlando Police Department, where she was credited with reducing violent crime and taking guns off the streets. Announcing her candidacy before a crowd of supporters gathered at the Orange County History Center, Demings said it was time to take her public service to Washington.

"I was relentless in my efforts to reduce crime and make Orlando a safer and stronger place to live, work and visit," she said. "But I am convinced that there is greater work for me to do."

Demings, who traded her police uniform for a royal-blue power suit Wednesday, eschewed attacks on Webster or even the Republican Party, saving her criticism for "Washington politicians." But her priorities were clearly in line with the Democrats: protecting the middle class, Social Security and Medicare while promoting job growth.

"While hard-working men and women hit the pavement every day in search of work or struggle to hold onto their house, we have a Congress that continues to reward millionaires and billionaires," she said.

Still, it's not entirely clear that Demings will stick with the 8th District. Boundaries might not be known for a year, and her home could be left out of it.

In the end, she could end up in a new district, facing a Democratic primary against former U.S. Rep. Alan Grayson, who has already announced his candidacy, and state Sen. Gary Siplin, who reportedly plans to run.

"I know there is a lot that needs to be done with the district lines and a lot could change, but today, Val Demings lives in Congressional District 8, and I have filed where I live," she said.

In a written statement, Webster campaign manager Kirsten Borman didn't mention Demings: "Our team is looking forward to running a strong campaign in 2012 based upon the issues. No matter what, Congressman Webster's priority remains job creation and fixing our country's addiction to reckless spending."

Orlando Mayor Buddy Dyer, who appointed Demings to the chief's post and introduced her at her campaign event, predicted she'll be a formidable candidate no matter whom she faces.

"It's hard to predict who her opponent or opponents will be," Dyer said. "I think Val can achieve about anything she sets her mind to."

Demings had worked for the department since 1984, working in criminal investigations, intelligence, internal affairs, tactical operations, drug enforcement and elsewhere. The sudden announcement of her departure in May fueled immediate speculation about her political future.

Dick Batchelor, a lobbyist and political analyst, said her record as chief of a major law-enforcement agency neutralizes the common Republican strategy of labeling Democrats as soft on crime.

Demings is charismatic and popular in Orlando, which apparently caught the eye of the Democratic Congressional Campaign Committee in Washington. She has already met with representatives of that committee and received their "blessing," Batchelor said.

"She's very smart, she's studied the issues, and she's a great communicator," Batchelor said.

Aubrey Jewett, a University of Central Florida political scientist, said Demings is a good candidate who is well known within Orlando's power structure. She has strong name recognition helped by her marriage to Orange County Sheriff Jerry Demings, he said.

But she has never run a campaign before. She has never raised campaign cash, Jewett said, and might have trouble winning a money race with Webster or Grayson. She also has to show voters she can do more than just fight crime.

"She'll have to show she's not a one-trick pony in policy," Jewett said.